The Women's Interagency HIV Study (WIItS) is a large, comprehensive cohort study designed to investigate a spectrum of questions relating to the pathogenesis and natural history of HIV infection among women in the era of highly active antiretroviral therapy. The purpose of this application is to extend support of the WIHS Data Management and Analysis Center (WDMAC) which will continue to provide leadership in contributing epidemiological and statistical expertise to the WIHS research agenda, provide a stable and efficient data management system, and provide coordination of study protocols and WIHS investigator initiatives to enhance the quality and validity of the data and the scientific research in the WIHS. The specific aims of WDMAC are: (1) To provide leadership in the design, analysis, and presentation of WIHS study data and to develop novel statistical and epidemiologic methodology applicable to the scientific research initiatives of the W1HS. A core component of this aim will be to distinguish factors associated with the normal aging process from HIV infection and the use of anti-viral therapies; (2) To establish, implement, and maintain a data management system encompassing data entry, transmission, documentation, editing, storage, and summarization. Components of this aim will be to establish a system for tracking the storage and transfer of biological specimens at the national repository, and produce annual public data tapes; (3) To establish and implement methods to coordinate research initiatives and scientific presentations, to facilitate communication among WIHS investigators, Working Groups, and Committees, to orchestrate revisions of study protocols and forms, and to produce study-wide profiles of cohort characteristics (WIHS Dossier), the study database and ongoing research initiatives (WDMAC Report), and scientific publications (WIHS Archives); (4) To implement a quality assurance program that integrates expertise in data management, study coordination, statistical methodology, and scientific disciplines. This program will promote adherence and training for standardized data collection and management programs. A key scientific initiative will build upon our existing cxperience to develop methods for the appropriate evaluation of the effects of therapies in observational studies.